1. Field of the Invention
The present invention relates to an automatic document feeder used in a copier or other image forming apparatus for feeding documents automatically.
2. Description of the Related Art
Hitherto, for example, in a copier, instead of having an operator place the documents one by one on the original platen glass, an automatic document feeder (ADF) is known for feeding the documents automatically onto the original platen glass. The known ADF is used by having the operator set the documents on the original tray, automatically feeding the documents one by one to the platen glass, executing copying by scanning each document with the optical system, and then sending out the documents automatically from above the original platen glass.
In such ADFs, a high speed mode can be selected in certain models. That is, after feeding the documents onto the original platen glass as mentioned above, the optical system scans the original from the home position and moves to the rear end of the original, and then returns to the home position. In this process, in order to copy as quickly as possible, high speed copying is realized by sending out the original when the optical system has finished scanning, without waiting until the optical system returns to the home position.
This document feeding timing for high speed operation is also the same for the final document.
However, when the final document is immediately discharged outside right after scanning, as described above, there may be a jamming, for example, while the paper on which the image has been transferred is being conveyed to the thermal fixing unit.
In such a case, the final document, once discharged outside, must be put back onto the original platen glass by the operator. This procedure is not only troublesome, but may involve the risk of returning a wrong document to the platen glass.